4i6 



DISEASES OF CULTIVATED PLANTS 



Sorauer, on the other hand, considers the disease under 

 consideration to be primarily due to frost. Small radial 

 cracks first appear in the bark, which gradually extend, and 

 if the callus that is formed is afterwards injured by frost, a 

 canker eventually results. I have at times met with such 

 cankered spots, on which no fungus could be found. 



Stems that are badly cankered should be removed and 

 burned. Small diseased patches may be cut out, and the 



FIG. 129. Coniothyrium Fuckelii, forming canker 

 on rose stems. 



wound dressed with tar. Giissow, who first observed this 

 disease, recommends that the earliest red patches indicating 

 the presence of the fungus on the young wood should be 

 painted with creosoted Stockholm tar. 



The rose canker, so common on the wood of many kinds 

 of roses, more especially Marechal Neil, and often most 

 abundant near the base of the stem near the junction of 

 stock and scion, is of a physiological nature, and has nothing 



